“The beauty of this study is that they tested people at different points and followed them [through to] autopsy,” Prashanthi Vemuri with the Mayo Clinic, who wrote an accompanying editorial but was not otherwise associated with the study, told Time.

“People need to know [this] and be aware that it is possible to slow down the decline of dementia,” said Vemuri, an Alzheimer’s expert.

One theory has been that it was encroaching disease that caused cognitive inactivity, said Wilson. The new research suggests it’s the other way around – that keeping intellectually stimulated can help slow memory loss and lessen the onset of dementia.

The study, published in the journal Neurology, found that older adults who were most active in late life showed a 32 percent slower rate of decline compared with those who maintained an average level of mental activity. And those who were the least active had a 48 percent faster fall into dementia, reported Time.

Rush and his colleagues began studying and testing more than 1,600 older adults in 1997. This study focused on nearly 300 who died at an average age of 89 and underwent a brain autopsy to look for changes associated with cognitive decline.

Even after adjusting for the effect of disease as well as for age and education, researchers still found that those who had engaged in mentally stimulating activities showed less brain damage.

The study doesn’t prove that being mentally active wards off cognitive decline, but Wilson said it’s another step toward that conclusion.

He also told Reuters that keeping one’s brain active should be enjoyable, not a chore. Book clubs, quilting, photography are all ways people can keep their minds busy and their brains healthier, he said.